Controlled loose stitching mechanism for chainstitch sewing machines



Sept. 9, 1969 F. L. WALLING 3,465,701

CONTROLLED LOOSE s rrrcame MECHANISM FOR CHAINSTITCH SEWING MACHINESFiled July 28, 1967 3 Sheets-Sheet l I l l l l l fl I I I l .9 IINVENTOR. Froncis L. Walling BY WITNESS: W .6144. Wad, JQMWAEQZ ATT EYSept. 9, 1969 F. WALLING CONTROLLED LOOSE STITCHING MECHANISM FORCHAINSTITOH' SEWING MACHINES 5 Sheets-Sheet 2 Filed July 28, 1967INVENTQR. Frunqi s L. Wollmg BY W'gORNEY WITNESS: d e/d; 594W Sept. 9,1969 F. WALLING CONTROLLED LOOSE STITCHING MECHANISM FOR CHAINSTITCHSEWING MACHINES 3 Sheets-Sheet 5 Filed July 28, 1967 I INVENTQR. FroncnsL. Wulimg BY v AT ORNEY WITNESS:

United States Patent CONTROLLED LOOSE STITCHING MECHANISM FORCHAINSTITCH SEWING MACHINES Francis L. Walling, Lincroft, N.J., assignorto The Singer Company, New York, N.Y., a corporation of New Jersey FiledJuly 28, 1967, Ser. No. 656,864 llnt. Cl. D0511 40/02 US. Cl. 112-245 4Claims ABSTRACT OF THE DISCLOSURE Brief summary of the invention In aconventional chainstitch sewing machine the amount of thread which isutimately used in the formation of each stitch may be controlled only byregulation of the usual thread tensioning devices. A disadvantage ofusing a thread tension device for providing loose stitches is that asthe tension is reduced, the entire stitch concatenation becomes looseand the limiting condition is soon reached in which the thread loopswhich chain between successive stitches become objectionably distended.

It is also known to produce loose stitching by means of a threadmetering device which cooperates with thread nippers. The thread nippersare rendered effective during portions of each stitch forming cycle andonly during periods of effectiveness of the nippers is thread drawn froma supply. A disadvantage of a system of thread handling which requiresthread nippers is that it does not respond to variations in thecharacter of the work.

The present invention provides -a needle thread metering and controllingmechanism for chainstitch sewing machines which provides for a widerange of preselected looseness in the stitches independently of thesetting of the thread tensioning device and which does not require theuse of a thread nipper. A plurality of thread controlling deviceseffective in seriatim on a needle thread between a conventional tensiondevice and the needle serve to draw out and (meter thread from a supplyduring the downstroke of the needle and to slacken the needle threadduring the upstroke of the needle. A stitch is thus provided in whichthe chain of loops which are set while the needle is down are laidneatly and in controlled fashion while the preselected looseness in thestitch occurs primarily in the needle thread bights from needlepenetration to needle penetration. A loose stitch formed in this mannerhas been found to be advantageously useful in sewing garments which mustthereafter be subject to heat treatment as, for instance, in the curingrequired for finishing permanent pressed garments. Stitched seams whichare tight when sewn, are usually puckered after such curing. By properpreselection of the degree of looseness in the stitches, the garmentseams after curing can be pucker-free and with the desired ultimatetightness.

Description of the drawings A preferred embodiment of the invention isillustrated in the acompanying drawings in which:

FIG. 1 represents a vertical cross-sectional view of a sewing machinehaving this invention applied thereto.

FIG. 2 is a top plan view of the sewing machine of FIG. 1 with the topcover removed.

FIG. 3 is an enlarged rear elevational view of a fragment of the bracketarm of the sewing machine of FIG. 1.

FIG. 4 is an enlarged cross-sectional view taken transversely of thesewing machine bracket arm substantially along line 44 of FIG. 2.

FIG. 5 is a perspective view of the thread controlling mechanism forboth the needle and looper threads of the sewing machine of FIG. 1.

FIG. 6 is a cross-sectional view taken substantially along line 66 ofFIG. 3, and

FIGS. 7, 8 and 9 represent diagramatic perspective views of the needleand loop taker together with a fragment of a work fabric and the needleand looper threads showing respectively the position of the parts andthreads at the uppermost of the needle, at engagement of the looperthread loop by the needle during the needle downstroke, and at thelowermost position of the needle.

Detailed description The sewing machine to which this invention isapplied as illustrated in the drawings includes a frame comprising a bed11 with a work supporting plate 12, a standard 13 rising from the bed,and a bracket arm 14 extending from the standard over the bed. Forconvenience of manufacture and assembly, the bracket arm 14- may beformed open at the top and at the free extremity, and these openings maybe closed by a top cover plate 15 and an end cover plate 16,respectively. It will be appreciated, however, that the cover plates 15and 16 form part of the bracket arm and may be made integral therewithif desired.

Carried lengthwise in the bed 11 is a rotary main shaft 20 having adrive pulley 21 fixed thereto. A thread carrying looper 22 is arrangedin the bed and is driven from the main shaft to partake of oscillationlengthwise of the looper for needle looper seizing and shedding, as wellas oscillation sideways of the looper to partake of needle avoidingmovement. To this end a rock shaft 23 journaled in the bed parallel tothe main shaft carries a support block 24 on which a looper carrier 25is journaled. The rock shaft 23 may be oscillated as by an eccentric orcrank drive (not shown) from the main shaft to impart needle avoidingmotion to the looper. A rock shaft 26 journaled transversely across thebed carries a rock arm 27 connected by a link 28 to the looper carrier25 to impart seizing and shedding oscillation to the looper. Aneccentric or crank drive (not shown) from the main shaft may be used tooscillate the rock shaft 26. The U.S. Patent of Clayton No. 2,394,510,Feb. 5, 1946, may be referred to for a detailed disclosure of this typeof looper oscillating mechanlsm.

As illustrated in FIGS. 1 and 5, spaced looper thread take-up disks 30fast on the main shaft 20 engage a thread from the looper as the threadpasses between a pair of thread guides 3131 and beneath a fixed threadengaging blade 32 extending between the take-up disks. From the take-updisks 30, the looper thread extends to a conventional thread tensioningdevice 33 and then to a supply (not shown). Preferably, the looperthread take-up mechanism is timed to draw in a loop of looper threadduring the loop shedding movement of the looper and to pay out the loopof looper thread during needle loop seizure by the looper.

Indicated at 35 in FIG. 1 is a feed dog of a conventional four motiondrop feed mechanism actuated by drive connection (not shown) from themain shaft 20. The feed dog 35 is opposed above the work supportingplate 12 by a presser foot 36 supported in the bracket arm 14.

Journaled lengthwise in the bracket arm 14 is an arm shaft which carriesa sprocket 41 driven by a timing belt 42 from a sprocket 43 on the mainshaft 20. This main shaft and the arm shaft are preferably connected bythe timing belt to rotate each at the same speed. Fixed at the freeextremity of the arm shaft 40 is a counterbalanced crank 44 including acrank pin 45 on which is pivoted a link 46 which embraces a stud 47 faston a needle bar 48. The needle-bar is slidably supported in bushings49-50 in the bracket arm 14 for endwise reciprocation in response toactuation by the crank 44 and carries at its lower extremity a needleclamp 51 fixing to the needle bar a thread carrying, eye pointed sewingmachine needle 52.

The needle thread controlling and metering mechanism of this inventionwill now be described and the path of the needle thread from the needleto a supply will be traced. From the needle 52 the needle thread extendsthrough a thread guide 59 secured on the needle clamp 51 and then to avery light thread tensioning device 60 on the bracket arm designed toprevent uncontrolled falling of thread toward the needle point as theneedle descends. The thread is then directed through an eyelet 61 in aforwardly extending thread take-up bracket 62 which is clamped securelyto the top of the needle bar 52 for reciprocation with the needle bar.From the take-up bracket 62, the thread extends to an eyelet 63 formedin an oscillating thread take-up arm 64 protruding through the frontwall of the bracket arm. The thread take-up arm 64 is clamped on a rockshaft 65 journaled within the bracket arm parallel to the arm shaft. Arock arm 66 on the rock shaft 65 is pivoted to a pitman 67 driven by aneccentric 68 on the arm shaft so as to oscillate the take-up arm 64preferably in synchronism with the reciprocation of the take-up bracket62 on the needle-bar. A thread guiding eyelet 69 formed on a wire loop70 clamped in selected position by a notched washer 71 and a clamp screw72 to the front of the bracket arm 14 receives the thread from thetake-up arm 64.

From the eyelet 69, the thread passes through a thread guiding tube 73which is fixed transversely across the top cover plate 15 of the bracketarm. The tube 73 is formed with a rounded mouth 74 at each end so thatthe thread may be passed from the front to the rear of the bracket arm.The tube 73, moreover, is skewed with respect to the lengthwisedirection of the bracket arm as illustrated in FIG. 2 so that the threadentering the tube mouth at the front from the general direction of thefree extremity of the bracket arm makes a bend of greater than 90degrees. Similarly at the tube mouth at the rear of the machine, thethread extending from the tube generally toward the standard 13 makes abend of greater than 90 degrees. The fractional resistance to movementof thread in the tube which arises due to these sharp bends particularlywhen the thread is taut, contributes to the favorable metering action ofthe mechanism of this invention as will be described more fullyhereinbelow. The skewed position of the tube 73, moreover, provides formore generous and convenient spacing of the thread controlling elementson the front and back of the bracket arm.

From the tube mouth 74 at the rear of the bracket arm, the thread passesthrough a pair of spaced thread guiding eyelets 80, 81 preferably formedas an integral wire frame 82. The wire frame 82 includes an elongateloop with substantially parallel limbs 8383 which, as illustrated inFIG. 6, are slidably constained in parallel notches 84S4 of a washer 85secured to the rear of the bracket arm by a screw 86. An oscillatingthread take-up arm protrudes through the rear wall of the bracket armand is adapted to oscillate in a path between the parallel links 83-83of the wire loop. The take-up arm 90 within the bracket arm is fast on arock shaft 91 which is substantially parallel to the arm shaft. A rockarm 92 on the rock shaft is pivotally connected to a pitman 93 driven byan eccentric 94 on the arm shaft. The take-up arm 90 is preferablydriven substantially in synchronism with the take-up arm 64 and take-upbracket 62 at the front of the machine. In other words, all three of themovable take-up elements 62, 64 and 90 move downwardly in unison duringdownstroke of the needle.

The washer 85 is oriented by the screw 86 so that the notches 8484 willconstrain the wire links 83-83 of the thread guiding eyelets one at eachside of and parallel with the path of motion of the thread takeup arm90. The vertical position of the eyelets 8081 relatively to the path ofmotion of the thread take-up arm 90 may be selected by the sewingmachine operator by turning a knob at the front of the sewing machinebracket arm. The knob is fast on a shaft 101 journaled in a dependingbracket 102 at the front of the bracket arm and a similar dependingbracket 103 at the rear of the bracket arm. A rock arm 104 fast on theshaft 101 at the rear of the bracket arm is connected by a pivoted link105 to the wire frame 82 beneath the constraining washer 85. Africtioning spring between the knob and the bracket 102 may be used toprevent drift or accidental turning of the knob 100.

The thread extending between the eyelets 8081 passes beneath the freeextremity of the take-up arm 90 so that on the downstroke of the take-uparm a loop of thread will be drawn in by the take-up arm. The threadloop will be prevented from sliding inwardly along the take-up arm 90 bythe parallel links 83-83 of the eyelet wire frame 82. From the eyelet81, the thread extends to a conventional thread tensioning device andthen to a supply (not shown).

The needle thread take-up bracket 62 and the oscillating needle threadtake-up arm 64 at the front of the machine operate in concert withrespect to the thread from the thread guiding tube 73 to the needle toprovide a slackening influence on the thread during the downstroke ofthe needle and to draw back and provide a tightening influence on thethread during the upstroke of the needle. Indeed the two movable threadtake-up elements 62 and 64 without more, provide substantially aconventional needle thread take-up arrangement for a chainstitch sewingmachine and if a thread were to be directed from a supply through aconventional tensioning device and then through the guide eyelet 69 andto the needle as described above, conventional needle thread handlingwould result in that the thread would be slackened on the needledownstroke and tightened on the needle upstroke to set the preceedingstitch and draw from the supply through the tension device an amount ofneedle thread equivalent to that used in the formation of the preceedingstitch.

The needle thread take-up bracket 62 and the oscillating needle threadtake-up arm, therefore comprise a first needle thread take-up meanseffective to influence the needle thread, as above described, betweenthe stationary thread guiding tube 73 and the needle.

The oscillating needle thread take-up arm 9 operating between the spacedeyelets 80, 81 at the rear of the sewing machine comprises a secondneedle thread take-up means which influences the thread in a manneropposite to that of the first thread take-up means; that is, the secondtake-u means draws back a loop of needle thread during the needledownstroke and pays out this loop of thread to slacken the needle threadduring the needle upstroke. By means of the operator influenced knob100, the position of the eyelets 80 and 81 may be regulated so as topreselect the amount by which the size of the loop of thread formed bythe second take-up means exceeds that manipulated or given up by thefirst take-up means.

As a result, during needle penetration on the downstroke of the needlethe combined effect of the first and second take-up means will be toremove all slack from the needle thread system and to draw into thesystem through the tensioning device 110 an amount of thread equal tothat used in the preceeding stitch formation. On the upstroke of theneedle a controlled slackness will exist in the needle thread so that aloose needle thread from one stitch to the next will be obtained. Thegreater the loop of thread formed by the second take-up means on theneedle downstroke, the looser will be the needle thread in the resultingstitches. This looseness will be maintained uniformly as betweensuccessive stitches even through the work thickness varies because thesecond take-up means will always meter through the tension device 110that amount of needle thread which was consumed in the immediatelyprevious stitch.

While needle thread is being metered from the supply through thetensioning device 110 by the second take-up means, the thread leading tothe needle will be taut and the frictional resistance to movementimposed upon the thread leading into and out of the tube 73 atrelatively sharp angles will accordingly be relatively high. As a resultthe tension which will exist on the needle thread in the vicinity of theneedle will be considerably lower than the tension which will exist onthe thread in the vicinity of the second take-up means.

FIGS. 7, 8 and 9 illustrate diagramatically various critical positionsof the stitch forming instrumentalities during a typical stitch formingcycle together with the disposition of the threads under the influenceof the controlling and metering mechanism of this invention. In thesefigures, N indicates the needle thread and L indicates the looperthread.

FIG. 7 illustrates the position of parts at the top of the needlestroke. The needle and looper threads in this position are both slackand as the work is fed the needle thread will drape loosely from oneneedle penetration to the next.

FIG, 8 shows the position of parts as the needle decends into the looperthread loop. Here the needle thread will be taut and it is in thisposition of parts that thread will be metered from the supply throughthe tensioning device 110. The needle thread loop from the previousneedle penetration will, however, remain on the looper in this positionof parts and thus prevent the concatenation of threads made at theprevious needle penetration from being drawn up tight.

FIG. 9 illustrates the position of parts at the bottom of the needlestroke. Both the needle and looper threads are taut at this point, andthe needle thread loop from the previous stitch will have been shed fromthe looper and will have shortened somewhat. The tension existing in thelooper thread at this time will, however, prevent the shed needle threadloop from shortening to any great degree and because of the impositionof friction resistance to the taut needle thread by the sharp angularbends on entering and emerging from the tube 73, the needle thread atthe stitching point will not be excessively tensioned. In the positionillustrated in FIG. 9 both the needle and looper thread take-upmechanisms have drawn back the maximum amount of thread and willimmediately thereafter begin to slacken the threads.

The resulting seam provided by the operation of the needle threadcontrolling and metering mechanism of this invention possesses aregulatable degree of looseness particularly in the needle thread sothat the stitched seam may later be subjected to processing such aspermanent press finishing which shrinks the sewing threads withoutresulting in puckering of the seam.

Having thus set forth the nature of this invention, what I claim hereinis:

1. A needle thread metering and controlling mechanism for a chainstitchsewing machine having a frame including a work support, a threadcarrying work penetrating needle mounted in said frame, and actuatingmeans in said frame for imparting endwise reciprocating movement to saidneedle, a needle thread tensioning device carried on said frame,stationary thread guide means carried on said frame for accommodating athread passing from said tensioning device to said needle, a firstmovable thread take-up means operatively connected with said actuatingmeans and effective to manipulate a loop of thread between saidstationary thread guide means and said needle for paying out said threadloop during the work penetrating stroke of needle reciprocation anddrawing in said thread loop during the withdrawal stroke of said needlereciprocation, a second movable thread take-up means operativelyconnected with said actuating means-and effective to manipulate a loopof thread between :said stationary thread guide and said tensioningdevice for drawing in said thread loop during the work penetratingstroke of needle reciprocation and paying out said thread loop duringthe withdrawal stroke of said needle reciprocation, and operatorinfluenced regulating means for preselecting the amount by which sizethe loop of thread manipulated by said second take-up means exceeds thesize of the loop of thread manipulated by said first take-up means.

2. A needle thread metering and controlling mechanism as set forth inclaim 1 in which said sewing machine frame includes a lengthwiseelongate bracket arm in which a needle-bar is mounted and in which saidfirst needle. thread take-u means is arranged at the front of thebracket arm, said second needle thread take-up means is arranged at therear of the bracket arm, and said stationary thread guide meanscomprises a thread guiding tube secured transversely from front to rearof said bracket arm.

3. A needle thread metering and controlling mechanism as set forth inclaim 2 in which said bracket arm is mounted to have a free extremityand in which said needle is mounted in the free extremity of saidlenghtwise elongated bracket arm, said thread guiding tube includes amouth at the rear and a mouth at the front of said bracket arm, both ofsaid tube mouths being from said extremity thereof, said first needlethread take-up means being located toward the free extremity of saidbracket arm from the tube mouth at the front of said bracket arm, saidsecond needle thread take-up means being located at the side oppositethe free extremity of said bracket arm from the tube mouth at the rearof said bracket arm, and in which a line joining said tube mouths isskewed relatively to the length of said bracket arm and provides forangles of greater than degrees in the thread leading into and out ofsaid tube mouths.

4. A needle thread metering and controlling mechanism as set forth inclaim 1 in which said second needle thread take-up means comprises athread engaging arm constrained to move in a predetermined path, a pairof thread guiding eyelets one at each side of the path of said threadengaging arm, means shiftably supporting said pair of thread guidingeyelets on said frame for movement in a path substantially parallel tothe path of said thread engaging arm, said operator influenced meanscomprising an operator influenced linkage carried on said frame andconnected to said pair of thread guiding eyelets for maintaining saidpair of thread guiding eyelets in selected position relatively to saidthread engaging arm.

References Cited UNITED STATES PATENTS 1,439,468 12/1922 Gatchell 1122411,569,992 1/1926 McCann 112--242 2,327,838 8/1943 Zeier 1l2246 2,626,5801/1953 Koenig 112-242 2,730,061 1/ 1956 Czajkowski 112--254 3,140,6827/1964 Hale et a1 112--242 MERVIN STEIN, Primary Examiner GEORGE H.KRIZMANICH, Assistant Examiner

